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Post by lowell on Aug 29, 2021 14:49:36 GMT -6
" By Michael Irving August 26, 2021"
'The James Webb Space Telescope has finally finished its testing regime and is getting ready for launch' NASA/Chris Gunn
'We don’t want to count our chickens just yet, but it looks like the James Webb Space Telescope (JWST) might actually launch in October, for real this time. The perennially delayed instrument has completed its final tests and is now being prepped for shipment to the launch facility.
Originally due to launch in 2007, the JWST underwent a drastic redesign and was given a new launch window of between 2015 and 2018. That later slipped to June 2019, then May 2020, then March 2021, and most recently to October 2021, thanks to the ongoing COVID-19 pandemic. Not to jinx it, but it’s looking like this latest launch date might actually stick.
NASA has finally given the telescope the green light for launch, having put it through years of tests and checkpoints to make sure that it will operate properly once it gets up there. After all, the JWST is bound for the second Lagrange Point in the Earth/Sun system almost a million miles away, so unlike Hubble, astronauts won’t be able to swing by for repairs and upgrades.
But that’s not space just yet – first it has to travel from the Northrop Grumman facilities in California to the launch site in Kourou, French Guiana, on the northeastern coast of South America. Once there, it will be packed into the Ariane 5 launch vehicle fairing, ready to leave Earth after all these years.
When it’s finally up and running, the James Webb Space Telescope will scan the cosmos in infrared for at least a decade, providing a deeper look in space and back in time than ever before. It will study the earliest light in the universe, peer closer at exoplanets, and give us our best shot yet at finding the first evidence of life beyond Earth. After the JWST aced all of its tests, engineers folded up its sunshield pallets, stowed the central tower, and locked it all together ready to be placed in a transporter container. These preparations, due to be completed in September, will get it ready to begin the next leg of its journey.'
Source: NASA
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Post by James T. Kirk on Aug 30, 2021 15:36:59 GMT -6
I wonder why it has to be shipped to South America.
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Post by lowell on Aug 31, 2021 1:42:02 GMT -6
NASA says "It is beneficial for launch sites to be located near the equator - the spin of the Earth can help give an additional push. The surface of the Earth at the equator is moving at 1670 km/hr."
It may also be true that it gives the Europeans a way to contribute to it, and justification for sharing what is learned with Europe. NASA doesn't work well with China and friction has grown between Russia and the U.S..
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Post by James T. Kirk on Aug 31, 2021 9:45:40 GMT -6
Well, with all the setbacks they've had I guess it's wise to optimize the outcome. I just hope they don't have any issues with it after it's up there, like they did with Hubble.
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Post by lowell on Aug 31, 2021 16:38:20 GMT -6
I was curious about whether this telescope will play a role in detecting gravity waves. It will be parked at the second Lagrange point, opposite from the Sun to the Earth.
"LAGRANGE is a space gravitational wave observatory design that maintains all important LISA science at about half the cost and with reduced technical risk. It consists of three drag-free spacecraft in the most stable geocentric formation, the Earth-Moon L3, L4, and L5 Lagrange points."
Since this observatory will be using one of the Lagrange points, it makes sense for it to work in tandem with the planned deployment of the LISA detectors at the rest of the Lagrange points.
LISA is the acronym for "Laser Interferometer Space Antenna". By putting one of these at each Lagrange point around the Sun, more accurate discovery of gravitational waves can be achieved.
"LISA is a space-borne Gravitational Wave Observatory with an arm-length of 2.5 million km, compared to the few km's of the ground-based observatories. LISA will enable us to discover the parts of the universe that are invisible by other means, such as black holes, the Big Bang, and other, as yet unknown, objects. LISA will enhance our knowledge about the beginning, evolution and structure of our universe."
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Post by lowell on Aug 31, 2021 16:45:38 GMT -6
'Why send the Webb telescope all the way out to L2? When astronomers began to think about where the Webb telescope should be placed in space, there were several considerations to keep in mind. To begin with, the Webb telescope will view the universe entirely in infrared light, what we commonly think of as heat radiation. To give the telescope the best chance of detecting distant, dim objects in space, the coldest temperatures possible are needed.
"A huge advantage of deep space (like L2) when compared to Earth orbit is that we can radiate the heat away," said Jonathan P. Gardner, the Deputy Senior Project Scientist on the Webb Telescope mission and Chief of the Observational Cosmology Laboratory at NASA's Goddard Space Flight Center in Greenbelt, Md. "Webb works in the infrared, which is heat radiation. To see the infrared light from distant stars and galaxies, the telescope has to be cold. Webb's large sunshield will protect it from both Sunlight and Earthlight, allowing it to cool to 225 degrees below zero Celsius (minus 370 Fahrenheit)." For the sunshield to be effective, Webb will need to be an orbit where the sun and Earth are in about the same direction.
With the sun and the Earth in the same part of the sky, the Webb telescope will enjoy an open, unimpeded view of the universe. In comparison, the Hubble Space Telescope is in low-Earth orbit where it goes in and out of the Earth's shadow every 90 minutes. Hubble's view is blocked by the Earth for part of each orbit, limiting where the telescope can look at any given time.
The Spitzer Space Telescope, another infrared telescope, is in orbit around the sun and drifting away from the Earth. Spitzer is already more than 100 million kilometers (60 million miles) away from the Earth, and eventually its path will take it to the other side of the sun. Once we can no longer communicate with Spitzer that means it is at the end of its mission life.
In contrast, a major perk of parking at L2 is the ease of communications. Essentially, the Webb telescope will always be at the same point in space. "We can have continuous communications with Webb through the Deep Space Network (DSN)," Gardner said. '
Without the Deep Space Network, communication with Lagrange point 2 would not be possible. (the Sun is in the way)
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